Smoke hood for electric furnaces and the like



n 1964 E. ERNI 3,138,649

smoxs HOOD FOR ELECTRIC FURNACES AND THE LIKE Filed Oct. 3, 1960 INVENTOR. E NR/CO E BY W 2). lmww United States Patent zerland Filed Oct. 3, 1960, Ser. No. 60,017 Claims priority, application Switzerland Oct. 6, 1959 3 Claims. (Cl. 13-15) The present invention relates generally to a protective covering or smoke shield for furnaces and, more particularly to a smoke hood particularly suitable for use in conjunction with open electrical furnaces.

It is well known that open electric furnaces employed for various metallurgical purposes generate substantial quantities of smoke during their operation which are both a nuisance and danger for the operators as well as for the surrounding community. Such generation of smoke and stack gases naturally does not occur in closed furnaces. However, since open electric furnaces are oftentimes employed in a wide variety of applications for pratcical reasons the problem of safely handling and exhausting the smoke is continually present when employing such furnaces. Up to the present it was common practice to permit the stack and smoke gases produced by these open electric furnaces to freely flow into the workshop from where they were removed by means of fines.

In accordance with the teachings of the present invention it is proposed to provide a novel smoke hood for effectively collecting the smoke and stack gases emerging from the furnace and operating independently of and without contact with the furnace charge while still safely ensuring protection of the working area around the furnace. In thus carrying out its required function, the smoke hood should also be designed to facilitate physical access to the furnace interior and permit visual observation thereof in a reliable and dependable manner under all operating conditions without unduly increasing the cost of its manufacture and installation. Accordingly, there is provided a smoke hood having a housing member consisting of a plurality of telescopically arranged wall portions adapted to be displaced relative to one another, said wall portions being arranged circumjacent an electrode holder member adapted to carry the electrode. The smoke hood is provided with insulating means suitably electrically insulating the electrode holder member from the slidable and telescopically arranged housing. The smoke hood may also be provided with one or more flues for directing the gases to a desired location. Additionally, it has been found advantageous to provide inspection windows on the housing member and also to provide the wall portions thereof with cooling compartments to prevent undue heating of the smoke hood by the effluent gases and smoke. The advantages of a smoke hood constructed in accordance with the teachings of the present invention resides in the fact that it can be installed on existing furnaces without great difficulty; it ensures protection against the smoke and gas emanating from the furnace even when the volume thereof is substantial; it readily permits visual inspection of the furnace interior; and the smoke hood can at all times be partially or fully raised for charging, checking, cleaning or any other desired operation so as to render accessible the furnace interior and the electrode.

Accordingly it is an important object of the present invention to provide means for removing gases emanating from a furnace in a safe and reliable manner.

It is a further object of the present invention to provide a novelly constructed smoke hood for open electric furnaces and the like which is relatively simple to manu- 3,138,649. Patented June 23, 1964 facture and can be easily installed on existing structures without undue difficulty or high installation costs.

It is another object of the present invention to provide means for conveying away undesirable waste gases from a furnace while permitting relatively easy physical and visual access to the furnace interior.

Yet another object of the present invention is the provision of a smoke hood for electric furnaces which can be easily accommodated thereon, is relatively simple in construction but highly efiicient in operation, and is safe during its operation.

These and still further objects of the present invention and its entire scope and applicability will become ap parent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

In the drawings:

FIGURE 1 is a vertical sectional view of the upper portion of an open electric furnace employing electrode means and provided with a smoke hood constructed in accordance with the teachings of the present invention;

FIGURE 2 is a plan view of the device shown in FIG- URE 1;

FIGURE 3 is an enlarged view of a wall portion of the smoke hood shown in FIGURE 1 and provided with a viewing window; and

FIGURE 4 is an enlarged View of a wall portion of the smoke hood shown in FIGURE 1 provided with cooling compartments.

Referring now to the drawings and, more particularly, to FIGURES 1 and 2 thereof, a smoke hood A is provided with an upper stationary annular wall member 1 supporting on its upper surface In one or more flues 2 communicating with the furnace interior via the apertures 2a. Disposed below the upper wall member 1 are the further wall members 3 and 4 which are arranged for sliding telescopic movement with respect to one another. Each of the wall members are provided with the laterally projecting annular ribs 1b serving to slidably interconnect adjacent wall members to permit said telescopic movement in order to expose the interior of a furnace 6 and its electrode 5 mounted in an electrode holder 7 circumjacent to which the smoke hood A is arranged. The left-hand portion of FIGURE 1 shows the housing of the smoke hood A consisting of the relatively movable wall members 1, 3 and 4 in raised position to permit access to the furnace interior, whereas the right-hand portion of FIGURE 1 shows the housing lowered almost to the extent of the upper surface 6a of the furnace. It is, of course, to be understood that any number of individual wall members may be employed depending upon the desired height of the smoke hood and the physical dimensions of the furnace to which it is applied.

Intermediate the flues 2 and the centrally arranged electrode holder 7 there is provided on the upper surface 1a of the upper wall member 1 an insulating ring 8 formed of an electrically non-conductive, mechanically and thermally stable material, as for example, asbestos, or a ceramic material or the like. This insulating ring 8 performs a dual function, to wit: it must on the one hand electrically insulate the current-carrying electrode holder 7 from the smoke hood A to safeguard against passage of current/to the smoke hood A and the furnace 6; Whereas, on the other hand, it must permit a relative movement of the electrode holder 7 with respect to the wall member 1 of said smoke hood in the direction of the double headed arrow BB to allow for a change -aldehye condensate. be dispensed with entirely and be replaced by a nonconductive layer, by way of example formed of mica,

formed on an organic or inorganic basis. provision of suitableinsulation means'is not particularly important-for the smoke hood A insofar as its ability'to remove smokeandwastegases is concerned, it ;is, howsections and using several electrodes.

awaeee of position of the electrode 5 without allowing considerable quantities of smoke or waste gases escaping at this point into the working area.

If the mechanical and thermal stresses applied to the 'insulatio1rring-8'are sufficiently low, this ring s'may also be formedof a synthetic material such as a phenol form- The insulating'ring 8 maynaturally or a sufliciently thermally stable insulating coating Although the ever, quite essential for practical reasons since completion ofa circuit between the-smoke hood A and the electrode ,5 must be absolutely prevented in view of the danger of accidents and'damage to the smoke hood itself.

Theparticularsmokeflues 2 employed must be suitably dimensioned in accordance with the prevailing condi- 'tions-of operation. The arrangement and operation of the apparatus and, in particular, the number of flues em- {ployed must be adapted to the volume of smoke desired to be removed. -Any known or conventional fluid conveying means such as fans, blowers, steam. ejectors or the like may be employedto aid in the exhaustion of the waste gases from the furnace.

In the embodiment shown in FIGURES 1 and 2, the

electric furnace-6 is provided with a circular cross-section and one electrode 5 is employed. understood that furnaces having other cross-sectional It is, of course, to be configurations and employing a plurality of electrodes maybe equipped with the smoke hood A designed according to the teachingsof the'present invention.

Thus, for example, the smoke, hood A may-obturate furnaces having rectangular, hexagonal, polygonal or oval cross- The hood must then naturally be designed with a correspondingly shaped cross-section so that-ibwill cover the entire furnace'interior andenclosesthe corresponding number of electrodes,'in -a manner illustrated in FIGURE .2. The smoke hood Ais preferably formed of sheet iron or steel. But'other metals, such-as aluminum, may also be advantageously employed while keeping under consideration thethermal stability-of thematerial to be employed.

The telescopically-displaceable members 3 and 4 are preferably designed'as shown in detail in FIGURE 3and are provided with the laterally extending rib portions or flanges 1b engaging adjacent flanges of the adjacently arranged wall portions topermitsuch sliding and telescopic movement as already detailed hereinaboveh The -r1b portions 1b not only serve to interconnect the respective wall portions 1, 3 and 4 of the smoke hood A but define limit stops for determining the extent of movement of said wall portions in their fully raised and lowered-positions. In order to-facilitate inspection of the furnace interior, at least some of the wall members may be providedwith windows 12 as clearly shown in.FIG-

'URE 3 in order to cover asuitably provided opening -'12a provided on. an associated wall member 9. The window jl2wmay be formed of any suitable transparent ing with the rib portion 1b and returned to said source via the flexible return conduit 14. Other possible cooling system depending on the conditions of operation of the smoke hood may be provided. If a water cooling system is provided which washes the entire outer surface of the telescopically displaceable members of the hood housing, care must be taken to ensure that the cooling medium does not enter the interior of the smoke hood.

It is, of course, possible to carry out raising and lowering movement of the displaceable wall members by means of mechanical means actuated by any conventional motor, or to provide a pulley system to gain a mechanical advantage in order to move the wall members relative to one another. Similarly, such raising and lowering movement can be carried out by any conventional pneumatic or hydraulic device.

-I claim:

1. The combination with an open electricfurnace having an electrode holder and an electrode member mounted in said holder, of a smoke hood mounted over and normally closing the open end of said electric furnace which comprises a housing member arranged circumjacent said ielectrode holder, said housingmember including separate adjacently arranged slidable wall members mounted *for telescopic .movement, said wall members being pro- 'vided with means supportably interconnecting-said adjacent wall members for sliding telescopic movement to permit raising and lowering of said Wall members to expose and obturate the interior of said open electric furnace.

2. The combination with an open electric furnace hav- .ing an electrode holder and an electrode member mounted in said holder, of a smoke hood mounted over and-nor- 'mally closing the open end of said electric furnace which comprises a housing member provided with a. plurality -of separate slidably arranged wall members disposed adjacent one another, said separate wall members each-being provided with rib portions-engageable with the rib portions ofan adjacently disposed wall member-permitting sliding and .telescopic movement of said housing. member into a retracted and extended-position, at least one of said wall members being provided with window means for exposingthe interior of the furnace when said housing member is in said extended position.

3. The combination with an open electric furnacehaving an electrode holder and an electrode member mounted insaid holder, of a smoke hood mounted over and normally closing the open end of said electric furnace which comprises a housing member provided with a plurality of separate slidably arranged wall members disposed adjacent one another, said separate wall members each being providedwith rib portions engageable with the-rib portions ofan adjacently disposed wall member-enabling sliding and telescopic movement thereof and defining 'a limit stop for movement of said wall members, flue means carried bysaid-housingmember in registry'with the interior of said electric furnace to remove gases therefrom, andinsulating means cooperable with said housing member to insulate thesame against leakage of current from the electrode through said housing member.

References Cited in thefile of. this patent UNITED STATES PATENTS 228,075 Illing May 25, 1880 806,648 Dickinson Dec. 5, 1905 818,003 Thorelius Apr. 17, 1906 913,465 Brouillet Feb. 23, 1909 2,210,370 Herradora Aug. 6, 1940 2,766,736 Del Buono Oct. 16, 1956 2,929,858 Koleda et a1 Mar. 22, 1960 FOREIGN PATENTS 198,255 Switzerland Sept. 1, 

1. THE COMBINATION WITH AN OPEN ELECTRIC FURNACE HAVING AN ELECTRODE HOLDER AND AN ELECTRODE MEMBER MOUNTED IN SAID HOLDER, OF A SMOKE HOOD MOUNTED OVER AND NORMALLY CLOSING THE OPEN END OF SAID ELECTRIC FURNACE WHICH COMPRISES A HOUSING MEMBER ARRANGED CIRCUMJACENT SAID ELECTRODE HOLDER, SAID HOUSING MEMBER INCLUDING SEPARATE ADJACENTLY ARRANGED SLIDABLE WALL MEMBERS MOUNTED FOR TELESCOPIC MOVEMENT, SAID WALL MEMBERS BEING PROVIDED WITH MEANS SUPPORTABLY INTERCONNECTING SAID ADJACENT WALL MEMBERS FOR SLIDING TELESCOPIC MOVEMENT TO 